Wickless candles

ABSTRACT

A wickless candle can be formed from a composition comprising 45 to 97.9 weight percent wax, 1 to 30 weight percent stearic acid and 1.1 to 25 weight percent ultrahigh molecular weight polyethylene. The wickless candle is easily ignitable, burns with little or no dripping and leaves little residue upon complete combustion. The wax can be a paraffin wax or a combination of paraffin wax and one or more of the following waxes: candellilla, carnauba, montan, spermaceti and beeswax. The ultrahigh molecular weight polyethylene refers to a polyethylene with a weight average molecular weight in the range of 500,000 to 6,000,000. The components of the composition are uniformly distributed therein.

United States Patent [72] inventors lrl N. Duling;

Richard D. Cassar, both of West Chester, Pa. [21] Appl. No. 840,529 [22]Filed July 9, 1969 [45] Patented Dec. 28, 1971 [7 3] Assignee Sun OilCompany Philadelphia, Pa.

[54] WICKLESS CANDLES 2 Claims, No Drawings [52] U.S. Cl 44/7.5, 431/288[5 l] Int. Cl C101 5/00 [50] Field of Search 44/75, 6, 7; 431/288,125,126

[56] References Cited UNITED STATES PATENTS 2,831,330 4/1958 Walker44/7.5 X

3,091,952 6/1963 Black 3,232,720 2/1966 Kepple ABSTRACT: A wicklesscandle can be fonned from a composition comprising 45 to 97.9 weightpercent wax, l to 30 weight percent stearic acid and 1.1 to 25 weightpercent ultrahigh molecular weight polyethylene. The wickless candle iseasily ignitable, burns with little or no dripping and leaves littleresidue upon complete combustion. The wax can be a paraffin wax or acombination of paraffin wax and one or more of the following waxes:candellilla, carnauba, montan, spermaceti and beeswax. The ultrahighmolecular weight polyethylene refers to a polyethylene with a weightaverage molecular weight in the range of 500,000 to 6,000,000. The

components of the composition are uniformly distributed therein.

WICKLESS CANDLES BACKGROUND OF THE INVENTION The invention relates to anovel candle formulation whereby no wick is required. It especiallyrelates to a candle formulation comprising paraffin wax, which maycontain other components normally used in candle formulation, andadditionally containing polyethylene with a weight average molecularweight in the range of 500,000 to 6,000,000. The addition of the latterto the candle formulation permits the manufacture of a candle without awick. The aforementioned polyethylene is also referred to as ultrahighmolecular weight polyethylene or UHMW PE. The invention also embraces awickless candle as an article of manufacture.

Much of the effort in improving candle performance has been directedtowards improvements in the performance of the wick. In Kirk and Othmer,Encyclopedia of Chemical Technology, Second Edition, Volume 4, underCandles" is a detailed description of the complex art involved inpreparing a satisfactory wick. Briefly, selected cotton yarn of certainphysical properties is interwoven or plaited into a wick. This plaitedwick is boiled in a weak alkali solution, bleached with chlorine orchlorine-containing solution with hydrochloric acid and washed withclean water. Excess water is removed. A specially prepared chemicalsolution is applied to the wick. After the water is removed the saltsremaining improve the burning characteristics of the wick and when theflame is extinguished prevents afterglow and smoldering. After soakingor boiling in the aqueous chemical solution, the composition of whichvaries greatly, depending upon the manufacturer, the wick is removed,dried and inspected. The wick is then wound on spools for use.

Consequently, a candle which performs satisfactorily but does notrequire a costly and difficult-to-make wick is highly desirable.

SUMMARY OF THE INVENTION The addition of 1.1 to 25 weight percent of thecomposition of UHMW PE to candle formulations permits the manufacture ofwickless candles. The elimination of the wick does not adversely affectthe candles performance. On the contrary a candle prepared using theimproved formulation of this invention performs highly satisfactorily.In addition to the UHMW PE the formulation comprises: 45 to 97.9 weightpercent paraffin wax or a combination of paraffin wax and one or more ofthe following waxes: candellilla, carnauba, montan, spermaceti andbeeswax; and l to 30 weight percent stearic acid.

DESCRIPTION The most common materials used as the major component incandles are the waxes. Specifically, various grades of paraftin waxeshaving melting points above 100 F. can be used. For example, a suitableparaffin wax can have a melt point between 127 F. and 156 F. (AMP); apenetration at 77 F. of from 9 to 33 (ASTM D-l 321 and a SayboltUniversal viscosity at 210 F. of 37.2 to 44.8 seconds. Other suitablewaxes include candellilla wax, carnauba wax, montan wax, spermaceti waxand beeswax. Combinations of waxes are sometimes used, one candleformulation reported in the literature contains 48 percent paraffin waxand 52 percent beeswax.

In addition to the above-described waxes a candle formulation cancontain stearic acid. The stearic acid is added for the purpose ofhardening the candle composition, raising the bending point, andlowering the melting point. Candle formulations can contain as much as30 weight percent stearic acid or as little as 1.0 weight percent. Onecandle formulation reported in the literature contains 70 percentparaffin wax, 10 percent beeswax and 20 percent stearic acid.

In addition to the above-described waxes and stearic acid candleformulations useful for the present purpose can contain a suitableamount of other additives such as antioxidants plus any other componentsnormally used by those skilled in the art in formulating candle waxcompositions. The latter category includes such components asreodorants, dyes and nonwaxlike materials which produce a particularburning'effect, i.e., chemicals, etc. For example, a candle formulationcan contain from 0.001 percent to 0.002 percent ditertiarybutyl-p-cresol as an oxidation inhibitor, and/or about 0.1 weightpercent of chinoline yellow as a dye.

The preparation of a candle using the formulation defined herein can beby most of the means known to the art; the exceptions being those meanswhichaCtuallyrequire a wick to build up a candle. An example of thelatter is the dipping process wherein a wick is repeatedly dipped into amolten candle composition to build up the candle.

Polyethylenes are available with a wide range of molecular weights.These molecular weights have a substantial effect on the properties ofthe polyethylene. For example a polyethylene with a molecular weight of1,500 is a waxy solid while a polyethylene with a molecular weight of1,500,000 is a hard, extremely tough solid. As discussed hereinmolecular weight refers to weight average molecular weight determined bylight scattering or solution viscosity or melt viscosity.

In the synthesis of polyethylene, not all the molecules grow to the samesize. The actual size variation depends upon the polymerizationemployed. Consequently, while the molecular weight of the UHMW PEreferred to in the examples herein is stated as being 1,500,000, thereare in fact individual molecules in the UHMW PE with molecular weightslower than 1,500,000 and even lower than 1,000,000. Sometimes, theindividual molecules have molecular weights as low as 500,000. Also inthe same 1,500,000 weight average molecular weight polyethylene thereare in fact individual molecules with molecular weights greater than2,000,000, sometimes the individual molecules have molecular weights ashigh as 3,000,000 or even as high as 6,000,000. Thus the polyethyleneused in this invention can have a weight average molecular weight in therange of 500,000 to 6,000,000.

Surprisingly the addition of an UHMW PE to candle formulations permitsthe manufacture of wickless candles that are easily ignitable despitethe lack of a wick. By easily ignitable it is meant that a safety match,in a windle'ss environment, will ignite the candle. Also once the candleis lit it continues to burn satisfactorily despite the lack of a wick.The wickless candle is essentially drip free. Drip or dripping is theobvious formation of molten material which flows over the periphery ofthe candle and which solidifies slowly as it falls down the side of theunit. Furthermore despite the lack of the wick the amount of unconsumedmaterial after complete combustion is extremely small.

The unexpected benefits of the present invention are dependent on theamount of UHMW PE used in admixture with the candle formulation. lf 5weight percent of UHMW PE is admix with a candle formulation 21 wicklesscandle prepared from the novel formulation can be easily ignited with asafety match whereas a wickless candle prepared from the same candleformulation but without UHMW PE cannot be ignited. However, as thepercent of UHMW PE admix with the formulation is in creased the ignitioncharacteristics of the formulation approaches that of only UHMW PE whichis extremely difficult to ignite with a match. 0n the other hand as theamount of UHMW PE in the candle formulation decreases, some lowerconcentration is reached where the amount of UHMW PE is not sufficientto cause any changes in the ignition characteristics of the candleformulation. Therefore it is desirable that the amount of UHMW PE in thecandle formulation be less than 50 weight percent, preferablyconsiderably less, and amounts even less than 5 weight percent areoperative. As a general rule, the amount of UHMW PE present in thecandle formulation should be in the range of 1.1 to 25 weight percentand sufficient to facilitate ignitability of the composition.

The relative volatilities and viscosities of the components of thecandle formulation and UHMW PE may help explain why a candle formulationcontaining 5 weight percent ignites whereas a candle formulationcontaining too low an amount of UHMW PE will not ignite. When an attemptis made to ignite a candle comprising paraffin wax and stearic acid witha match, the molten wax and molten acid, because they are not veryviscous, flow rapidly away from the flame. Because both of the moltenmaterials flow so fast, not enough material vaporizes to start a flameand without sufficient vaporization no flame can be obtained. Thus arelatively low concentration of UHMW PE in the candle formulation doesnot significantly alter the phenomenon just described. However 5 weightpercent UHMW PE does alter the just-described phenomenon. In otherwords, when an attempt is made to ignite a candle comprising paraffinwax, stearic acid and 5 weight percent UHMW PE with a match, the moltencombination of wax, acid and UHMW PE is very viscous and thus flows awayslowly from the flame. Because the melted components flow so slowly,enough wax and/or acid material is vaporized by the flame to start andmaintain a flame. Once the flame is sustained by vaporizing wax and/oracid molecules the UHMW PE vaporizes, or decomposed portions of UHMW PEvaporize, thus contributing to the flame and the UHMW PE too isconsumed.

In order that the heretoforementioned viscosity-volatility interplayexist during combustion the UHMW PE must be uniformly distributedthroughout the candle. One way of achieving this uniform distribution isto add the UHMW PE as a fine powder to agitated molten candleformulation, maintained at a temperature below the melting point of theUHMW PE and then allow the combination to solidify while being agitated.A preferred way of achieving this uniform distribution of UHMW PE in theformulation is as follows. UHMW PE powder is added rapidly to theagitated molten formulation maintained at a temperature above themelting point of the UHMW PE and the latter becomes uniformlydistributed therein probably in a state of molecular dispersion. As soonas the polyethylene gels the formulation, the homogeneous mass isallowed to cool without agitation. In the solid mass the polyethylenemolecules are apparently uniformly distributed throughout the wax and byhaving a sufficient number of molecules present the molecules areconnected together in a random fashion. This molecular connection occurswith 5 weight percent of polyethylene, 75 weight percent wax and 20weight percent stearic acid but does not occur if the percentpolyethylene is too low. The connecting together of the UHMW PEmolecules results in a sort of molecular polyethylene sponge in whichthe voids are filled with wax and acid.

EXAMPLES A typical paraffin wax, used herein for illustrative purposes,has a melting point of 127 F. (AMP), a viscosity at 210 F. of 43.6 SUS,a penetration at 77 F. of 33 (ASTM D-1321 and an oil content of 0.5percent (ASTM D-72l AMP refers to the American Melting Point which is anarbitrary figure 3 F. higher than the ASTM melting point. A typical UHMWPE, used herein for illustrative purposes has a weight average molecularweight of 1,500,000; a specific gravity of 0.94 (ASTM D-792), acrystalline melt point of 275 F. as determined by differential thermalanalysis and a nil melt index (ASTM D-l 238). A typical stearic acid,used herein for illustrative purposes, has a melting point of l33 F. Alower molecular weight polyethylene, used herein for illustrativepurposes, had a molecular weight of about l00.000. A microcrystallinewax also used herein for illustrative purposes had a melting point of 1F. (ASTM D-l 27).

The compounding of the paraffin wax, stearic acid and UHMW PE wasperformed in the following manner. Seventyfive parts of paraffin wax andparts of stearic acid were melted in a suitable container. Thetemperature of the molten combination was maintained at a few degreesabove the melting point of the UHMW PE. While the molten combination wasbeing agitated 5 parts of UHMW PE powder were rapidly added. Soonthereafter the polyethylene gelled the combinatton. After this gelattonthe combination, without agitation,

was allowed to solidify into a candlelike shape.

For comparative purposes wickless candlelike shapes were prepared from(1 only the heretoforementioned wax; (2) the heretoforementioned wax andvarious weight percents of UHMW PE; (3) the heretoforementioned wax andstearic acid; (4) the heretoforementioned microcrystalline wax; (5) theheretoforementioned microcrystalline wax and the UHMW PE; and (6) onlythe UHMW PE.

These wickless candle-shaped bodies were tested as to their case ofignition. Ease of ignition was determined by whether the preparedwickless candle could be ignited with a safety match in a windlessenvironment. After ignition the burning candles were observed as to theamount of dripping. As shown in the following table a wickless candlecomprising 75 weight percent paraffin wax, 20 weight percent stearicacid and 5 weight percent UHMW PE ignited easily and burned withessentially no dripping.

TABLE Candle Additive, Candle Formulatinn Weight Test Result l Paralfinwax None Would not ignite 2 Paraffin wax UHMW PE, Would not ignite |.0%3 Paraffin wax UHMW PE, Easily ignited,

2.5% burns with essentially no dripping 4 Paraffin wax, None Would notignite wt. Ia. and

Stearic acid.

20 wt. 5 5 Parafl'in wax. UHMW PE, Easily ignited,

75 wt. in. and 5% burns with Stearic acid. essentially no 20 wtv l1dripping or smoking. very little residue 6 Paraffin wax PE. 5% Would notignite 7 Microcrystal- None Would not ignite line wax 8 Microcrystal-UHMW PE. Ignites, burns line wax 5% with su stantial dripping, largerestdue 9 None UHMW PE Difficult to ignite but will burn Polyethylenewith a molecular weight of |00.000

Substantially equivalent results as for the above candle 5 are obtainedwhen (1) other paraffin waxes or mixtures thereof with herein specifiednonpetroleum waxes are used and/or (2) other ultrahigh molecular weightpolyethylenes are employed.

The invention claimed is:

l. A wickless candle composition comprising wax having uniformlydistributed therein stearic acid and polyethylene;

a. said wax being paraffin wax or a combination of paraffin wax and oneor more of the following waxes: candellilla, carnauba, montan,spermaceti and beeswax;

b. said acid being present in amount between l and 30 weight percent ofthe composition; and

c. said polyethylene having a weight average molecular weight in therange of 500,000 to 6,000,000 and being present in amount between 1.1and 25 weight percent of the composition and sufficient to facilitateignitability.

2. A wickless candle according to claim 1 wherein the paraffin wax has amelting point from 127 F. (AMP) to 156 F. (AMP).

2. A wickless candle according to claim 1 wherein the paraffin wax has amelting point from 127* F. (AMP) to 156* F. (AMP).